Bit of a strange one. This issue was happening on the previous Kstars and again last night on the latest release.

I'm using an ASI1600 and Stellarmate run off an RPi4 4GB and monitor over VNC. Everything is fine 95% of the time. If I'm in the middle of an image plan and I pause it or stop it, for example, I'm not happy with an autofocus result and I pause the plan to focus again, Kstars will close unexpectedly without warning. It's happened a few times now. The strange thing is, the camera cooler keeps running even after Kstars crashes. When I start it up again, I connect everything as normal. At first I was starting the cooler but I noticed the the ammeter on my PSU was rising an amp for a few seconds and then dropping off again for a few seconds. The temperature would fluctuate between -18 to -21 repeatedly when it should be at -20. I found out that if I switch the cooler off after a crash it remains at a steady -20 which is the temperature the camera was set to before the crash. Ekos reports that the cooler is running at 0%. Pics attached. Any ideas why its crashing in the first place?

Yes, seen this, too. When you have kstars crash it won't properly disconnect the devices and INDI. They will just continue running. Guess that's not a bug after all.
You should also see that when you restart kstars and fire up EKOS all devices will be connected (I have set it to not autoconnect).

Open terminal and run KStars in gdb:
if the program crashes, type in bt to get the backtrace and post it.

Nope. Everything disconnects, mount stops tracking etc. Even PHD looses its connection and has to be reconnected. Even when I disconnect everything at the end of the session, the camera cooler stays on until I shut down the RPi.